Unable to create an instance of the handler for command - FastEndpoints

Question

I am trying to call handler in FastEndPoint. This is my EndPoint code

public override void Configure()
    {
        Post("/api/claim/create");
        //TODO: after Auth0 integration will add auth
        AllowAnonymous();
    }
    public override async Task HandleAsync(ClaimRequest req, CancellationToken ct)
    {
        await new CreateClaim()
        {
            ClaimName = req.ClaimName
        }.ExecuteAsync();
    }

I defined my class that inherit CommandHandler class and implements ExecuteAsync() of base class. But i am getting runtime exception.

I followed this link https://fast-endpoints.com/docs/command-bus#_2-define-a-command-handler